🔌 Sermonizer

A simple, clean serial monitor with a clean terminal UI for embedded development.

Most terminal-based serial monitors are annoying to use - they have clunky interfaces and no sane defaults. We wanted something that could be quickly spun up to interact with embedded devices during firmware development without any hassle.

┌Serial Monitor────────────────────────────────────────────────────────────────────────────────┐
│[2026-09-10 09:41:02.118] I (312) boot: ESP-IDF v5.2                                          │
│[2026-09-10 09:41:02.121] I (318) wifi: connecting to lab-iot                                 │
│[2026-09-10 09:41:03.877] I (2074) wifi: got ip 192.168.4.23                                  │
│> [2026-09-10 09:41:07.402] AT+GMR                                                            │
│[2026-09-10 09:41:07.410] AT version:2.4.0.0                                                  │
│[2026-09-10 09:41:07.411] OK                                                                  │
│[sermonizer] device disconnected: Broken pipe - reconnecting (Ctrl+C to quit)                 │
│[sermonizer] device reconnected                                                               │
│[2026-09-10 09:41:12.006] I (309) boot: ESP-IDF v5.2                                          │
│[2026-09-10 09:41:12.009] I (315) main: sensor=23.4C hum=41%                                  │
│                                                                                              │
│                                                                                              │
└──────────────────────────────────────────────────────────────────────────────────────────────┘
┌Input─────────────────────────────────────────────────────────────────────────────────────────┐
│AT+CWJAP="lab-iot","                                                                          │
└──────────────────────────────────────────────────────────────────────────────────────────────┘
 ttyUSB0 115200 8N1  follow | LF | Enter send, Up/Down history, Shift+Up/Down PgUp/PgDn scroll,

Received lines, a sent line (>, shown with --echo), sermonizer's own notices and the line still being received. Regenerate with just update-screenshot.

Features

• Smart auto-scroll: Follows new data, easy to switch to manual scrolling
• Auto-reconnect: Keeps watching the port and resumes when the device comes back
• Clean TUI: Split view with input at bottom, output on top, status bar with connection state
• Auto-detect ports: Just run sermonizer and it finds your device; dead onboard UARTs stay out of the way unless you ask for --all-ports
• Sane defaults: 115200 baud, 8 data bits, no parity, 1 stop bit
• Hex mode: View binary data as hex bytes with a hexdump -C style ASCII column
• Clean text: ANSI colour codes from firmware logs are stripped (keep them with --raw)
• Local echo: --echo shows what you sent, for devices that do not echo
• Logging: Save RX/TX data with timestamps
• Fast: Built in Rust, handles high baud rates smoothly

Quick Start

# Install from crates.io
cargo install sermonizer

# Install from source
git clone https://github.com/systemscape/sermonizer.git
cd sermonizer
cargo install --path .

# Or run locally
cargo run --release

# Connect to first available port
sermonizer

# Or specify port and baud
sermonizer --port /dev/ttyUSB0 --baud 115200
# Or with cargo run
cargo run --release -- --port /dev/ttyUSB0 --baud 115200

# List available ports
sermonizer --list
# Or with cargo run
cargo run --release -- --list

Usage

sermonizer [OPTIONS]

Options:
  -p, --port <PORT>        Serial port path
  -b, --baud <BAUD>        Baud rate (default: 115200)
      --line-ending <E>    Line ending: none|nl|lf|cr|crlf (default: nl)
      --data-bits <N>      Data bits: 5|6|7|8 (default: 8)
      --parity <P>         Parity: none|odd|even (default: none)
      --stop-bits <N>      Stop bits: 1|2 (default: 1)
      --flow-control <F>   Flow control: none|software|hardware (default: none)
      --dtr <on|off>       Set the DTR line after opening
      --rts <on|off>       Set the RTS line after opening
      --hex                Display data as hex
      --raw                Keep ANSI escape sequences instead of stripping them
  -e, --echo               Show sent lines in the output, prefixed with "> "
  -w, --wrap               Wrap long lines instead of clipping them
      --mouse              Scroll output with the mouse wheel
      --log <FILE>         Log received data
      --tx-log <FILE>      Log transmitted data
  -t, --timestamps         Add timestamps to display and logs (alias: --log-ts)
      --list               List available ports
      --all-ports          Also list ports of unknown type (e.g. /dev/ttyS*), hidden by default

Controls

• Type and press Enter: Send data to device
• Paste: Multi-line text is sent line by line; an unfinished last line stays in the input box
• ↑↓: Browse send history
• Home / End, Ctrl+A / Ctrl+E: Jump to start / end of the input line
• Ctrl+U / Ctrl+K / Ctrl+W: Delete to start of line / to end of line / previous word
• Shift+↑↓ / Page Up/Down: Scroll through output
• Shift+Home / Shift+End (or Ctrl+Home / Ctrl+End): Jump to top / bottom of output (End resumes auto-scroll)
• Mouse wheel: Scrolls the output when started with --mouse. It is off by default because capturing the mouse makes most terminals require Shift+drag to select and copy text
• Ctrl+T: Toggle wrapping of long lines
• Ctrl+L: Clear output
• Ctrl+V, then a key: Send that key as a raw control byte (e.g. Ctrl+V Ctrl+C sends 0x03)
• Esc: Clear input line
• Ctrl+C / Ctrl+D: Exit

Why?

Perfect for:

• Arduino/ESP32 debugging
• Firmware development workflows
• Quick embedded device interaction
• Protocol testing and development

License

MIT - see LICENSE file.